If you're having trouble importing or exporting to a field in Salesforce because it won't appear in the dropdown picklist of fields you should check the following:
Is the field marked as "Hidden"? If so then SigParser won't be able to see it.
Field level security rules may limit which fields the user you connected to Salesforce from SigParser is able to see. You should check if that user can see the field.
SigParser doesn't allow mapping to some of the standard managed package fields that must be set by SigParser in a particular way.
Some fields aren't updatable so they won't be available to map data into.
Some standard fields cannot be mapped. These include
Contact
Email
AccountId
Account
Website
Coworker to Contact
RecordTypeId
Id
OwnerId
...SigParserUID__c
...Internal_Email_Address__c
...Last_Sync_Time__c
...Email_Address__c
...Contact__c
Coworker to Company
RecordTypeId
Id
OwnerId
...SigParserUID__c
...Matched_Domain__c
...Internal_Email_Address__c
...Account__c
...Last_Sync_Time__c